That is due to flaws in the WEP algorithm, not due to the
passphrase length. WEP with 8 or 800 character passphrase is just
as vulnerable.

Why is it a horror? You only had to enter the passphrase once on
each device. It is not something you had to do every day or even
every week.

My work involves experimenting a lot with different add-ons so I am always entering it. I've since memorized it but it takes time to enter it correctly with these keyboards.

I never said that the relative insecuritiy of WEP was due to the length of the passphrase. Only that it was a horror because it's long, and nothing to do with being the cause of that more insecuret choice.